About 80 people are missing, although the government hasn't confirmed the exact number. A New Zealand military plane using radar found a small wooden dinghy on Sunday that was carrying seven survivors who told rescuers the ferry sank.
Kiribati, which has about 108,000 people, declared a week of prayer as the search for more survivors continued. The U.S. and Australia have joined New Zealand in the search, as have several fishing boats in the area.
Government spokesman Tearinibeia Enoo-Teabo said maritime authorities had ordered the MV Butiraoi, a 17.5-metre (57-foot) wooden catamaran, not to carry any passengers before it left because it had sustained serious damage to its navigational system, rudders and hull. It was unclear whether any repairs had been made.
He said investigators are going to the island to find out more about the passenger count and why the ferry left despite the orders.
Other questions remain, including why it took Kiribati authorities so long to tell New Zealand officials the ferry was missing.
The ferry left Nonouti Island bound for South Tarawa on Jan. 18, according to authorities, a journey which was supposed to take two days. New Zealand rescuers said they weren't told about the missing boat until Friday, eight days after the ferry had left.
Enoo-Teabo said they believe at least 80 passengers and five crew members were aboard.
New Zealand's Rescue Coordination Centre said they're continuing to search for a more substantial life raft that may have been launched from the sinking ferry and which was designed to carry 25 people.
The seven survivors told rescuers they had drifted for four days in the blazing sun and had no water. They were found more than 180 kilometers (112 miles) from the nearest major island.
The crew of the Orion plane dropped supplies to the survivors and then a fishing boat picked them up. They have since transferred to a Kiribati marine patrol with a doctor aboard. New Zealand authorities identified the survivors as three men, three women, and a 14-year-old girl. All are described as being in reasonable health.
Meanwhile, the Nonouti Island Council (NIC) has completed a survey and released the names of its entire people who were passengers of the sunken ferry MV Butiraoi.
Women Interest Worker (WIW) on the island Toaraa Nooa told Radio Kiribati News the survey which was based on the collecting and compiling of passenger names, was conducted on every village on the island from Temotu to Abamwakoro.
Toaraa said the Council confirmed from the survey that a total of 88 people boarded the vessel from the island with 45 men and 43 women.
After categorising the passengers, the Council found out that there were 65 adults, 13 high school students and 10 primary-aged children.
Photo file: Caption MV Butiraoi